This project was initiated to study the mechanism of chemical carcinogenesis by employing the technique of quantitative two-dimensional electrophoresis of total cellular proteins. This type of electrophoresis allows the simultaneous separation of hundreds of polypeptides in a single polyacrylamide gel. We have acquired, and have significantly expanded, a computer-based system to automatically analyze autoratiograms produced from these gels. This system automatically finds and measures the amount of radioactivity in any polypeptide resolved by these electrophoretograms. Programs were developed which automatically match together the spot patterns found in different gels. Stil other programs link together a series of gels which may constitute an experiment, and allow the investigator to quantitatively follow the synthesis of any resolvable protein through that experiment, or series of experiments. The investigator may specify various parameters and ask the computer to list those spots whose pattern of synthesis may lie within those parameters. Finally, several sophisticated computer-graphics programs allows the investigator to visually compare and follow various polypeptides which may be matched on a virtually unlimited number of electrophoretograms.